Dataset Information

Adaptive evolution of virus-sensing toll-like receptor 8 in bats.

ABSTRACT: Recently, bats have gained attention as potential reservoir hosts for emerging zoonotic single-stranded (ssRNA) viruses that may prove fatal for humans and other mammals. It has been hypothesized that some features of their innate immune system may enable bats to trigger an efficient early immune response. Toll-like receptors (TLRs) represent a first line defense within the innate immune system and lie directly at the host-pathogen interface in targeting specific microbe-molecular patterns. However, the direction and strength of selection acting on TLRs are largely unknown for bats. Here, we studied the selection on viral ssRNA sensing TLR8 based on sequence data of 21 bat species. The major part (63 %) of the TLR8 gene evolved under purifying selection, likely due to functional constraints. We also found evidence for persistent positive selection acting on specific amino acid sites (7 %), especially when compared to viral TLR evolution of other mammals. All of these putatively positively selected codons were located in the ligand-binding ectodomain, some coincidenced or were in close proximity to functional sites, as suggested by the crystallographic structure of the human TLR8. This might contribute to the inter-species variation in the ability to recognize molecular patterns of viruses. TLR8 evolution within bats revealed that branches leading to ancestral and recent lineages evolved under episodic positive selection, indicating selective selection pressures in restricted bat lineages. Altogether, we found that the TLR8 displays extensive sequence variation within bats and that unique features separate them from humans and other mammals.

SUBMITTER: Schad J

PROVIDER: S-EPMC7079948 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Adaptive evolution of virus-sensing toll-like receptor 8 in bats.

Schad Julia J Voigt Christian C CC

Immunogenetics 20160809 10

Recently, bats have gained attention as potential reservoir hosts for emerging zoonotic single-stranded (ssRNA) viruses that may prove fatal for humans and other mammals. It has been hypothesized that some features of their innate immune system may enable bats to trigger an efficient early immune response. Toll-like receptors (TLRs) represent a first line defense within the innate immune system and lie directly at the host-pathogen interface in targeting specific microbe-molecular patterns. Howe ...[more]

PMID: 27502317

Similar Datasets

Project description:Members of the family Suidae have diverged over extended evolutionary periods in diverse environments, suggesting that adaptation in response to endemic infectious agents may have occurred. Toll-like receptors (TLRs) comprise a multigene family that acts as the first line of defense against infectious microbes at the host-environment interface. We hypothesized that across the Suidae, positive selection mediated by infectious agents has contributed to the evolution of TLR diversity. Thus, we analyzed Sus scrofa, Sus barbatus, Sus verrucosus, Sus celebensis, Sus scebifrons, Babyrousa babyrussa, Potamochoerus larvatus, Potamochoerus porcus and Phacochoerus africanus genomes. Specifically, analyses were performed to identify evidence of positive selection using Maximum likelihood (ML) methods within a phylogenetic framework for bacterial and viral sensing Suidae TLR extracellular domains. Our analyses did not reveal evidence of positive selection for TLR3 and TLR7, suggesting strong functional conservation among these two genes for members of the Suidae. Positive selection was inferred for Suidae TLR1, TLR2, TLR6 and TLR8 evolution. ML methods identified amino acid sites of the bacterial sensing TLR1, TLR2, TLR6 and the viral sensing TLR8 to be under persistent positive selection. Some of these sites are in close proximity to functionally relevant sites, further strengthening the case for pathogen mediated selection for these sites. The branch leading to the genus Sus demonstrated evidence of episodic positive selection for TLR1, indicating selection mediated by infectious agents encountered within the specific geographic origin of the Sus. These results indicate that species of the Suidae have positively selected residues within functional domains of TLRs reflective of prior infections. Thus, TLR genes represent candidates for experimental validation to determine their functional role in antibacterial and antiviral activity within members of the Suidae.

Dataset Information

Adaptive evolution of virus-sensing toll-like receptor 8 in bats.

Publications

Adaptive evolution of virus-sensing toll-like receptor 8 in bats.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets